From the FAQ's > Logic Pro and MainStage 64-bit mode FAQ
You can switch between 32-bit and 64-bit mode following these steps:
- Quit Logic Pro or MainStage if it is running.
- Navigate to the Logic Pro or MainStage application in the Applications folder.
- Choose Get Info from the Finder File menu.
- Disable the option to "Open in 32-bit mode" to open in 64-bit mode.
You would have to have Logic installed to view that infromation from the Logic > Get Info window.
On the RAM upgrade, the more RAM for audio editing the better. I'd increase beyond 4GB of RAM is possible.